我正在尝试使用PHP从mySQL数据库获取数据。这是我第一次真正尝试远程获取数据;使用JSON。php文件运行正常,因为它在浏览器中以JSON字符串的形式输出,并且我使用JSONLint对其进行了赋值。所以,我不确定我在这里做错了什么。如有任何帮助,将不胜感激
这就是LogCat抛出的:
Error parsing data org.json.JSONException: Value <?xml of type java.lang.String cannot be converted to JSONObject
threadid=9: thread exiting with uncaught exception (group=0x401dce20)
FATAL EXCEPTION: Thread-10
java.lang.NullPointerException
at com.andaero.test.JSON.JSONMain$1.run(JSONMain.java:39)
at java.lang.Thread.run(Thread.java:1020)
UPDATE:我根据Mark的请求从php文件中删除了echo方法。我认为这与"JSONArray a=json.getJSONArray("regulatory")有关。我也尝试了其他人的方法,但没有成功。
以下是类别:
public class JSONfunctions {
public static JSONObject getJSONfromURL(String url) {
InputStream is = null;
String result = "regulatory";
JSONObject jArray = null;
// http post
try {
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Log.e("log_tag", "Error in http connection " + e.toString());
}
// convert response to string
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
Log.e("log_tag", "Error converting result " + e.toString());
}
try {
jArray = new JSONObject(result);
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
return jArray;
}
}
列表活动:
public class JSONMain extends ListActivity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listview);
final ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
new Thread(new Runnable() {
public void run() {
JSONObject json = JSONfunctions
.getJSONfromURL("http://192.168.1.34/andaero/regulatory_list_ASC.php");
try {
JSONArray a = json.getJSONArray("regulatory");
for (int i = 0; i < a.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = a.getJSONObject(i);
map.put("id", String.valueOf(i));
map.put("label", e.getString("label"));
map.put("title", e.getString("title"));
map.put("caption", e.getString("description"));
map.put("dummy", e.getString("gotoURL"));
mylist.add(map);
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
}
}).start();
ListAdapter adapter = new SimpleAdapter(this, mylist,
R.layout.list_item, new String[] { "label", "title", "caption",
"dummy" }, new int[] { R.id.label, R.id.listTitle,
R.id.caption, R.id.dummy });
setListAdapter(adapter);
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
@SuppressWarnings("unchecked")
HashMap<String, String> o = (HashMap<String, String>) lv
.getItemAtPosition(position);
Toast.makeText(JSONMain.this,
"ID '" + o.get("id") + "' was clicked.",
Toast.LENGTH_SHORT).show();
}
});
}
}
PHP:
<?php
//MySQL Database Connect
include 'andaerologin.php';
mysql_select_db("andaero");
$sql=mysql_query("select * from regulatory_list");
$output = array();
while($row = mysql_fetch_assoc($sql)) {
$output['regulatory'][] = $row;
}
exit (json_encode($output));
mysql_close();
?>
尝试将您的PHP更改为:
$output = new stdClass();
$output->regulatory = array();
while($row = mysql_fetch_assoc($sql)) {
$output->regulatory[] = $row;
}
header('Content-type: application/json');
echo (json_encode($output));
尝试将您的PHP脚本更改为:
<?php
// Hide errors to prevent data corruption
ini_set('display_errors', 0);
// For debugging, uncomment these lines to show errors
//ini_set('display_errors', 0);
//error_reporting(E_ALL);
//MySQL Database Connect
require 'andaerologin.php';
if (!mysql_select_db("andaero")) {
// Use trigger_error() so you can find out in the server logs if something
// goes wrong
trigger_error('Unable to select MySQL database');
header('HTTP/1.1 500 Internal Server Error');
exit;
}
$query = "SELECT *
FROM regulatory_list";
if (!$result = mysql_query($query)) {
trigger_error('MySQL error: '.mysql_error());
header('HTTP/1.1 500 Internal Server Error');
exit;
}
if (!mysql_num_rows($query)) {
trigger_error('MySQL returned no results');
header('HTTP/1.1 500 Internal Server Error');
exit;
}
// Build an array of the results
$output = array();
while ($row = mysql_fetch_assoc($result)) {
$output[] = $row;
}
// Send the results back as JSON
exit(json_encode($output));
// Closing the database connection happens implicitly at the end of the
// script. Also, you don't need to have a closing PHP tag at the end of the
// file and omitting it is a good habit to get into as it can avoid problems
在您的PHP代码中,更改
json_encode($output)
至
json_encode($output, JSON_FORCE_OBJECT)
JSON_FORCE_OJECT选项需要PHP版本>=5.3.0
您的问题似乎在jArray = new JSONObject(result);
我不知道JSONObject
构造函数需要什么,但我知道您正在向它发送一个JSON数组,而不是一个对象。
您真的需要表中的所有字段吗?
我曾经做过同样的操作,SELECT*FROM表和json_encode()所有结果。jQuery在读取数据时似乎遇到了问题,尽管JSON结果看起来非常好。
因此,我试图限制数据,并通过SELECT field1、field2 FROM表仅向浏览器发送所需字段,而不是所有字段。
然后一切都很好。我只能怀疑jQuery可以解析的JSON数据量是有限的。
我知道你没有使用jQuery,但我只是把我的经验留在这里以防万一。